1.Why do we need wrapping film (not just "cling film")?
Moisture and Rust Prevention (Core Function):
Cold-rolled coils are high-precision steel products that have undergone pickling and cold rolling. Their clean surface makes them highly susceptible to rust when exposed to humid air. Stretch film forms a physical barrier, effectively isolating moisture and salt from the air (especially during coastal or sea transport), preventing rust during transportation and short-term storage.
For even higher rust prevention requirements, VCI (Vacuum Phase Inhibitor) films are used. This film slowly releases rust-inhibiting components within a confined space, adhering to the surface of the steel coil and providing stronger active rust protection.
Dust and Contamination Prevention:
During transportation (especially by road), dust, oil, and mud splashes from rain can contaminate the clean surface of the steel coil, affecting subsequent processing (such as painting and welding) or directly leading to customer complaints. Stretch film keeps the product clean.
Security and Protection:
It effectively secures the steel coil to the underlying wooden or steel support (saddle), preventing slight displacement during transport.
Protect the edges of the steel coil to prevent friction or collision with other goods.
2.In what situations is it "not necessary" or should other methods be used?
Immediately proceed to the next process: If cold-rolled coils are transported directly within the factory to an adjacent continuous annealing line, galvanizing line, or color coating line for processing after coming off the rolling mill, packaging is usually unnecessary.
Products with special coatings or treatments: For example, galvanized coils (GI/GL) and aluminized zinc coils have a zinc coating that provides excellent rust protection. For short-distance transport or short storage periods, simple dust protection may be sufficient, or even just corner protectors and inner diameter protective sleeves, without full wrapping.
Customer explicit requirements: Some downstream customers may accept or request simple packaging to reduce costs, depending on their usage (e.g., immediate unwinding).
Special rust protection requirements: For long-distance sea transport or harsh environments, more advanced packaging may be used, such as composite packaging with VCI rust-proof film + rust-proof paper + desiccant + waterproof/vapor barrier (e.g., thick plastic sheeting), rather than just a single layer of stretch film.
3.What are the applicable situations for general industrial stretch film?
Ordinary cold-rolled coils suitable for domestic land transportation, short-term storage, and general rust prevention requirements.
4.What are the applicable situations for VCI vapor phase corrosion inhibitor film?
Export sea freight, coastal transportation, high value-added products (such as automotive steel sheets and appliance steel sheets), and medium- and long-term warehousing.
5.What are the applicable situations for simple packaging (corner protectors/inner sleeve only)?
Short-distance transportation of galvanized/aluminized zinc coils, in-plant turnover, and special agreements with customers.